Circuit card files of a type exemplified by my prior U.S. Pat. No. 3,258,650 issued June 28, 1966 have found widespread use in recent years, the use extending to electronic equipment employed in a number of diverse environments, some of which are quite adverse. A most common adversity is that of shock and vibration, which is experienced in vehicular installations, military ordinance installations, and equipment which includes moving comonents. The effects of shock and vibration are manifested in several detrimental effects. For instance, the cards themselves are constructed of dielectric materials which are somewhat brittle and subject to the development of cracks if permitted to vibrate. Cracks are intolerable, as they can extend across circuit patterns and cause interruption of the conductive pth and consequent malfunction, to say nothing of structural weaking. Another instance is the tendency of a vibrating card to work loose from its electrical connection or to develope high resistance at the contacts.
In order to alleviate problems of shock and vibration, circuit card files of the prior art have been structured to include a hinged retaining bar across the front or open face of the file. The retaining bar may be swung on its hinge axis to a position where it is clear of the front face to permit removal and insertion of cards. After the cards are in place, the bar is swung into position where a resilient engagement face bears against the exposed edges of the cards to retain them in place. While the retaining bar of the prior art is effective to prevent the cards from working loose from their electrical connector, it falls short of providing adequate restriction of vibration in a direction normal to the plane of the card, for the resilient nature of the engagement face imparts sufficient flexibility to permit vibration. Hence, the development of resistence at the connectors and damage to the card itself is not adequately alleviated. Moreover, a serious problem is incurred by virtue of the abrasive effects of the vibrating card edge on the resilient material of the retaining bar engagement face itself, which is abraded away to a point of ineffectiveness in a surprisingly short period of use.